Alcohol inhibits and disinhibits sexual behavior in the male rat

Abstract

Anecdotal evidence from human case studies suggests that alcohol exerts opposite effects on sexual behavior: facilitation at low doses and disruption at higher doses. We tested this dosedependent dual-effect hypothesis in Experiment 1 by assessing the effects of a wide range of doses of alcohol (0.25 to 2.0 g/kg, i.p.) on the copulatory behavior of sexually active male rats. Rather than the predicted dual effect, all doses of alcohol disrupted copulation, with the highest blocking it completely. Because the facilitatory effect of alcohol on human sexual behavior is believed to reflect a release from inhibition, we hypothesized that the facilitatory effect of low doses of alcohol might be found only when sexual responding was inhibited. In Experiment 2, we tested this hypothesis by assessing the effects of two doses of alcohol (0.5 and 1 g/kg), both of which had proven disruptive in Experiment 1, on the sexual behavior of male rats that had learned to inhibit their sexual behavior during tests with sexually nonreceptive females. Following injection with the lower dose, most of the previously nonresponsive males mounted the nonreceptive females and ejaculated without ever gaining vaginal intromission. These results provide the first experimental evidence that alcohol can inhibit or disinhibit the copulatory behavior of male rats depending upon dose and upon the absence or presence, respectively, of sexual inhibition. © 1989, Psychonomic Society, Inc.. All rights reserved.